Spiral spring



Feb. 27, 1940.

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Patented Feb. 27, 1940 PATENT. OFFlCE SPIRAL SPRING Leonard C. Peskin,Worcester, Mass, assignor to The American Steel and Wire Company of NewJersey, a corporation of New Jersey Application June 8, 1937, Serial No.147,119

2 Claims. (Cl. 26'71) This invention relates to the use of coil springsfor powering purposes, such as their use in watches, clocks, and topower automatic moving picture cameras. One of the objects is to use allof the available elastic energy of bending provided by such springs.Another object is to reduce the friction existing between their adjacentconvolutions during coiling and uncoiling. Other objects may beinferred.

The accompanying drawing illustrates three specific examples of coilsprings embodying the features of the present invention, the variousfigures being as follows:

Figure 1 is a side view of the first example.

Figures 2 and 2" illustrate a second example in side and sectionalviews, respectively.

Figure 3 is a third example.

Figures 4 and 5 are modifications of this third example.

In the case of the first example, the inner end of a coil spring I isfixed to a suitable shaft or spindle 2, and its outer end is aperturedas at 3, so as to provide an opening through which a bent end of a wirelink 4 may be passed, the other end of this link beingsimilarly bent andanchored by a pivot pin 5. The position of this pivot pin and the lengthof this link are such that its end connecting with the outer end of thecoil spring swings in a substantially radial direction respecting theaxis of the coil spring. It will be noted that this link 4 pivotsrespecting both the outer end of the coil spring and the anchoring pivotpin.

As a result of the above arrangement the outer end of the coil spring isanchored against tangential movement respecting the spring but isentirely free to move radially towards and from the spring while thelatter is coiling and uncoiling, the rate of this movement beingapproximately proportional to the rate of coiling and uncoiling of thespring, while the extent of the movement is between two extremepositions respectively spaced from the axis of the coil spring distancessubstantially equaling the diameters of the spring in its coiled anduncoiled extremes. The method of operating the coil spring thus involvedis obviously different from the usual arrangement wherein the outer endof the coil spring is held not only against tangential movementrespecting the spring but against radial movement as well.

When the outer end of the coil spring is fixedly anchored in the usualmanner, a considerable length of the spring remains after coiling whichundergoes no bending as a curved bar but which is essentially a straightbeam between its fixed end and a relatively remote point of tangency onthe coiled remainder of the spring, and under such forces as to resultin a large amount of friction being created by the various convolutionsbeing virtually pushed against one another, whereby a great deal of theavailable elastic energy of bending in the coiled spring is absorbed inovercoming this friction. Furthermore, when the outer end is fixed therelatively straight length of wire left at this outer end after coilingcontributes little to the useful elastic energy of the spring as awhole, this energy being mainly the result of the changes in radiiundergone by the curved portions of the spring during the uncoilingoperation. These various effects also result in stress concentrationsfrequently leading to premature spring breakages.

The present invention which teaches freeing the outer end of the springto movement or fioating action radially respecting the spring, whileholding this end against tangential movement respecting the same,permits the spring to act more nearly as a continuously curved beamthroughout its entire length, whereby the ineffective straight piece of.spring otherwise remaining at the end of the coil is eliminated. Also,because of the radial freedom of the end of the spring undesirableradial forces are eliminated at this point, which results in a moreconcentric seating of one coil convolution upon another during coiling,friction between adjacent convolutions of the spring is considerablyreduced and the stresses are uniformly distributed. It follows that thepresent invention considerably increases the efficiency and life of acoil spring as contrasted to the characteristics of the same spring whenits outer end is fixedly anchored.

A further advantage incidental to the invention is one pertaining to themanufacture of the spring. This follows from the fact that it is notnecessary to anneal the ends of the spring lengths to provide the shapedends heretofore necessary in many of these springs, it being possible tocut the hardened steel strip from which the spring is made while, at thesame time, punching the opening required for the link.

In the case of the second example of the invention, the outer end of thespring I is sandwiched between the ends of a looped strip 6, by means ofrivets I, the anchorage being effected by a pin 8 passed through thisloop and riding in a straight guideway 9 extending radially respectingthe axis of the coil spring. This guideway 9 may be provided by suitableslots formed in the spring housing where the latter is used or can beused. In the case of this example, the pin 8 moves or floats radially toprovide the results of the swinging end of the link 4 in the case of thefirst example.

The third example consists of two coils l0 and H of spring metal striparranged with their outer convolutions interconnected by a straightsection I2 extending tangentially from one of the coils to the other.The two coil springs thus provided may be formed from a single length ofstrip or may be formed from separate pieces with their respective endsspliced together, as at 13, or interconnected by a wire link l4, theselatter two arrangements constituting the first and the secondmodifications of this third example. It is obvious that during thesimultaneous coiling or uncoiling of coils l0 and II through themechanism of an interconnecting gear works or similar device thestraight section l2 anchoring their respective outer ends may floatradially respecting the Working coil while, at the same time, thenecessary tangential anchoring is effected.

It is to be understood that although preferable, it is not necessary toanchor the springs completely against tangential movement. Some slighttangential movement will not result in inand a wire link having bentends respectively engaging said pin and said end, the latter beingengaged by way of said hole, said link pivoting on said pin andpivotally swinging with said end during working of said spring.

2. The combination of a spiral spring having an outer end ofapproximately the same hardness as the remainder of the spring andthrough which a hole is formed, anchored pivot means spaced from saidend in approximate alignment therewith and a link having one end bentand engaging said endof said spring by way of said hole and its otherend connecting with said means, said link pivoting respecting said meansand. pivotally swinging with said end during working of said spring. I

LEONARD C. PESKIN.

